The present invention relates to ink guides for ballpoint pens, and more particularly the present invention relates to such an ink guide which allows a ballpoint pen to replaceably use different ink cartridges of different concentration.
Various ballpoint pens have been proposed, and have appeared on the market. FIG. 1 illustrates a ballpoint pen according to the prior art which comprises a reservoir tube filled with ink and held inside a barrel, a ballbearing attached to an absorbent rod, which is connected to the reservoir tube by a connector. The ink is continuously absorbed by the absorbent rod and guided out of the steel ball in the ballbearing during writing. As the absorbent rod keeps absorbing the ink even if it is saturated with the ink, the leakage of the ink may occur easily. There is also known in the prior art another ballpoint pen arrangement, as shown in FIG. 2, which comprises a barrel having an ink chamber on the inside to contain the ink, a tubular plug inserted into the barrel to hold a ballbearing and an absorbent rod. The absorbent rod continuously absorbs the ink, and then applies the ink to the steel ball in the ballbearing for writing. This ballpoint pen arrangement increases the ink holding capacity, however, it does not eliminate the leakage of the ink. Another problem of either of the aforesaid two ballpoint pen arrangement is that the ballpoint pen will become useless and shall be thrown away when the ink is used up. If the ballpoint pen of either structure is refilled with a different ink, the refilled ink may cause a chemical reaction with the residue of the ink previously used, to block the ink passage. Further, the assembly process of either ballpoint pen is complicated. It is difficult to control the best distance between the steel ball of the ballbearing and the tip of the absorbent rod. Since the distance between the tip of the absorbent rod and the steel ball of the ballbearing determines the flow rate of the ink to the steel ball, the ballbearing should be properly fastened to the absorbent rod, and accurately checked by an instrument after assembly.